from pydantic_settings import BaseSettings


class Settings(BaseSettings):
    app_name: str = "Awesome API"
    admin_email: str

from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str
    description: str | None = None
    price: float
    tax: float | None = None
    tags: set[str] = set()


@app.post(
    "/items/",
    response_model=Item,
    summary="Create an item",
    description="Create an item with all the information, name, description, price, tax and a set of unique tags",
)

#### `lru_cache` 技术细节

`@lru_cache` 修改了它所装饰的函数，以返回第一次返回的相同值，而不是再次计算它，每次都执行函数的代码。

因此，下面的函数将对每个参数组合执行一次。然后，每个参数组合返回的值将在使用完全相同的参数组合调用函数时再次使用。

例如，如果您有一个函数：
```Python
@lru_cache
def say_hi(name: str, salutation: str = "Ms."):
    return f"Hello {salutation} {name}"
```

您的程序可以像这样执行：

```mermaid
sequenceDiagram

participant code as Code
participant function as say_hi()

from typing import Union

from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str
    description: Union[str, None] = None
    price: float
    tax: Union[float, None] = None
    tags: list[str] = []


@app.post("/items/")
async def create_item(item: Item) -> Item:
    return item


@app.get("/items/")
async def read_items() -> list[Item]:

from fastapi.testclient import TestClient
from typing_extensions import Annotated


def dependency_list() -> List[str]:
    return []


DepList = Annotated[List[str], Depends(dependency_list)]


def create_dependency(name: str):
    def fun(deps: DepList):
        deps.append(name)

    return Depends(fun)


router = APIRouter(dependencies=[create_dependency("router")])

from typing import Set, Union

from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str
    description: Union[str, None] = None
    price: float
    tax: Union[float, None] = None
    tags: Set[str] = set()


@app.post(
    "/items/",
    response_model=Item,
    summary="Create an item",

		{"text/*,application/json", []string{"text/*", "application/json"}, true},
	}

	for _, testCase := range testCases {
		testCase := testCase
		t.Run(testCase.str, func(t *testing.T) {
			gotPatterns, err := parseCompressIncludes(testCase.str)
			if !testCase.success && err == nil {
				t.Error("expected failure but success instead")
			}
			if testCase.success && err != nil {

from fastapi import FastAPI

app = FastAPI()


@app.get("/items/{item_id}")
async def read_user_item(item_id: str, needy: str):
    item = {"item_id": item_id, "needy": needy}

app = FastAPI()


class Item(BaseModel):
    name: str
    description: Union[str, None] = None
    price: float
    tax: Union[float, None] = None


@app.put("/items/{item_id}")
async def update_item(
    item_id: Annotated[int, Path(title="The ID of the item to get", ge=0, le=1000)],
    q: Union[str, None] = None,
    item: Union[Item, None] = None,
):
    results = {"item_id": item_id}

from typing import Union

from fastapi import FastAPI
from pydantic import BaseModel

app = FastAPI()


class Item(BaseModel):
    name: str
    description: Union[str, None] = None
    price: float
    tax: Union[float, None] = None
    tags: set[str] = set()


@app.post("/items/", response_model=Item, tags=["items"])
async def create_item(item: Item):
    return item


@app.get("/items/", tags=["items"])